In many places and situations where telecommunications are used, a number of people share the use of a plurality of telecommunications terminals. For example: in telemarketing systems such as automatic call-distribution (ACD) systems, individual agents can serve calls from any terminal in the system; on a factory floor, all workers share use of a limited number of telephones; in a security system, at a commercial building or a prison, security guards must be able to perform their function at any of the system's telecommunications terminals; and in a field sales office where salespersons spend most of their time in the field, the office is often efficiently equipped with only a small number of desks each one of which has a voice and data terminal, and individual salespeople, when they are in the office, use whichever desks are not occupied at that time.
Since people are distinct individuals and not fungible entities, the telecommunications system needs to know which terminal is presently being used by which person, so as to provide proper operation. For example, in the ACD system, the identity of the agent who is presently using a terminal needs to be known so that an accounting system can credit the correct agent with handling the calls that are handled at that terminal. In the security system, the identity of the guard who is presently using the terminal needs to be known to distinguish agents from impostors and to keep track of the guards. In the factory system, the identity of the worker who is presently using a telephone needs to be known to determine whether that worker has privileges to call outside of the factory and to charge the correct worker for long-distance calls. And in the sales office, the identity of a salesperson who is presently using a terminal needs to be known so that incoming calls for salespeople can each be directed either to the proper salesperson's desk if he or she is in the office, and to a voice mail system if he or she is not in the office. In these situations it is also difficult, if not impossible to determine a person's present location, e.g., for receipt of emergency calls, and paging plus callback channels must be used to overcome this lack of knowledge.
In order to keep track of which person is presently using which terminal, advanced telecommunications systems require the person to log on to the telecommunications system from a terminal prior to using the terminal, and require the person to log off when he or she is done using the terminal. Examples of various types of these systems abound in the prior art. Unfortanately, all of them appear to have constraints on the services which they can provide the features which they can support, and the telecommunications equipment which they can adapt to. For example, some require users to have their own terminals and to take these from place to place with them. Others require all terminals in the system to be identical. Some consider a terminal to be vacant (e.g., out-of-service) when no one is logged in at the terminal. Some support only ACD-types of services. Others are suitable only for use with electronic messaging systems. Some treat all users of a terminal the same and are incapable of providing different capabilities and features to different users. And others differentiate between different users only for purposes of one direction, e.g., incoming or outgoing, of call origination.